cros: Add a setting for the Launcher's 'Continue Reading' feature.

This cl adds a setting to toggle the Launcher's 'Continue Reading' feature.

Bug: 843839, 872481
Test: manual.
Change-Id: I071e955194edcdf8f3184668b00f60fd8f2de71c
Reviewed-on: https://chromium-review.googlesource.com/1170317
Commit-Queue: Tao Wu <wutao@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583482}

chrome/app/settings_strings.grdp

@@ -2471,6 +2471,12 @@
   <message name="IDS_SETTINGS_WAKE_ON_WIFI_DESCRIPTION" desc="In the settings tab, the text next to the checkbox for enabling quickly reconnecting to known Wi-Fi SSIDs.">
     Keep Wi-Fi on during sleep
   </message>
+  <message name="IDS_SETTINGS_APP_LIST_CONTINUE_READING" desc="In the settings tab, the text next to the checkbox for enabling Continue Reading in Launcher.">
+    Continue Reading
+  </message>
+  <message name="IDS_SETTINGS_APP_LIST_CONTINUE_READING_DESCRIPTION" desc="Secondary, continued explanation of what is Launcher continue reading.">
+    Resume viewing sites from mobile on your Chromebook
+  </message>
   <message name="IDS_SETTINGS_MANAGE_CERTIFICATES" desc="Text for manage certificates button in Privacy options">
     Manage certificates
   </message>

chrome/browser/extensions/api/settings_private/prefs_util.cc

@@ -431,6 +431,10 @@ const PrefsUtil::TypedPrefMap& PrefsUtil::GetWhitelistedKeys() {
   (*s_whitelist)[ash::prefs::kDockedMagnifierScale] =
       settings_api::PrefType::PREF_TYPE_NUMBER;
 
+  // App list settings.
+  (*s_whitelist)[prefs::kAppListContinueReadingEnabled] =
+      settings_api::PrefType::PREF_TYPE_BOOLEAN;
+
   // Input method settings.
   (*s_whitelist)[::prefs::kLanguagePreloadEngines] =
       settings_api::PrefType::PREF_TYPE_STRING;

chrome/browser/resources/settings/privacy_page/privacy_page.html

@@ -146,6 +146,13 @@
                 aria-describedby="clearBrowsingDataSecondary"></button>
           </paper-icon-button-light>
         </div>
+<if expr="chromeos">
+        <settings-toggle-button
+            pref="{{prefs.app_list.continue_reading_enabled}}"
+            label="$i18n{enableAppListContinueReading}"
+            sub-label="$i18n{enableAppListContinueReadingDescription}">
+        </settings-toggle-button>
+</if>
         <div class="settings-box" on-click="onMoreSettingsBoxClicked_"
             hidden="[[!unifiedConsentEnabled_]]">
           <div class="start">$i18nRaw{syncAndPersonalizationLink}</div>

chrome/browser/ui/webui/settings/md_settings_localized_strings_provider.cc

@@ -1937,6 +1937,9 @@ void AddPrivacyStrings(content::WebUIDataSource* html_source,
       {"enableContentProtectionAttestation",
        IDS_SETTINGS_ENABLE_CONTENT_PROTECTION_ATTESTATION},
       {"wakeOnWifi", IDS_SETTINGS_WAKE_ON_WIFI_DESCRIPTION},
+      {"enableAppListContinueReading", IDS_SETTINGS_APP_LIST_CONTINUE_READING},
+      {"enableAppListContinueReadingDescription",
+       IDS_SETTINGS_APP_LIST_CONTINUE_READING_DESCRIPTION},
       {"manageCertificates", IDS_SETTINGS_MANAGE_CERTIFICATES},
       {"manageCertificatesDescription",
        IDS_SETTINGS_MANAGE_CERTIFICATES_DESCRIPTION},